An American Airlines mechanic charged with sabotaging a plane because he was upset over stalled labor contract negotiations was fired from another airline several years ago and briefly had his mechanic’s license suspended, according to court documents.

Abdul-Majeed Marouf Ahmed Alani appeared in federal court in Miami on Friday on a charge of willfully damaging or disabling a plane. Federal investigators say he admitted to tampering with a part that provides vital flight information to pilots.

The pilots aborted the July 17 flight before takeoff in Miami. Alani, 60, was arrested Thursday. He had worked for American since 1988 but was suspended after his arrest.

Court records from a lawsuit in California indicate that for some years, Alani worked both for American and Alaska Airlines until Alaska fired him in 2008 after several errors including failing to verify that repairs were working and installing the wrong battery on a plane. The Federal Aviation Administration suspended his mechanic’s certificate for 30 days, according to court documents.

Alani, who was born in Iraq and became a U.S. citizen in 1992, sued Alaska Airlines for discrimination based on national origin. A judge dismissed the lawsuit for lack of evidence.

The lawsuit and Alani’s firing by Alaska were first reported by Business Insider.